Brainstem Strokes Flashcards
cortical findings of stroke
*language abnormalities
*gaze preferences
*neglect syndromes
*cortical sensory findings
*personality changes
*hemibody symptoms
4 types of herniation
- subfalcine herniation
- transtentorial central herniation
- transtentorial uncal herniation
- cerebellar (tonsillar) herniation
subfalcine (cingulate) herniation
*lateral displacement of the cingulate gyrus beneath the falx cerebri
*can cause compression of ACA, leading to ischemia/stroke
*causes a midline shift!
*main symptom = drowsiness
transtentorial central herniation
*caudal (downward) displacement of the temporal lobe and brainstem
*can cause rupture of basilar artery branches, leading to hemorrhages in midbrain and upper pons
transtentorial uncal herniation
*occurs when the uncus (medial temporal lobe) is squeezed downward past the tentorium cerebelli
*can compresses CN III and cause oculomotor palsy and/or ipsilateral hemiparesis
cerebellar (tonsillar) herniation
*herniation of the cerebellar tonsils through the foramen magnum
*can result in compression of the lower brainstem, leading to dysregulation of cardiac and respiratory centers, coma, and death
left (dominant) MCA syndrome
*aphasia
*right homonymous hemianopsia
*right hemiparesis (arm > leg)
*right hemisensory loss
*left gaze preference
right (nondominant) MCA syndrome
*left neglect (hemiattention)
*left homonymous hemianopsia
*left hemiparesis (arm > leg)
*left hemisensory loss
*right gaze preference
ACA syndrome
*very uncommon
*hemiparesis (leg > arm/face)
*gaze preference
*sensory loss (leg > arm/face)
*behavioral disorders
*incontinence
PCA syndrome
1. contralateral homonymous hemianopia or cortical blindness if bilateral
2. visual behavioral disorders (palinopsia, prosopagnosia, alexia, color anomia)
*temporal lobe involvement may cause aphasia and memory loss
*thalamic involvement can cause sensory loss
cerebellum - overview
*coordination center of the brain
*responsible for motor timing
*all output from the cerebellum is inhibitory
*main motor output: dentate -> cerebellar peduncle -> contralateral red nucleus -> thalamus - motor cortex
symptoms of cerebellar dysfunction
*dizziness
*ipsilateral ataxia
*nausea/vomiting
*double vision
*difficulty with balance
small-vessel (lacunar) syndromes
*small, deep infarcts in the distribution of the lenticulostriates, thalamoperforators, or paramedian branches of the basilar
*25% of strokes
*pathology is fibrinoid necrosis, lipohyalinosis, and microatheroma
*risk factors = HTN, DM, tobacco abuse, hyperlipidemia
*NO CORTICAL FINDINGS ON EXAM
5 classic lacunar syndromes
- pure motor hemiparesis (internal capsule or ventral pons)
- pure sensory stroke (thalamic stroke/lesion)
- clumsy-hand, dysarthria syndrome (pons or internal capsule)
- sensorimotor stroke (often thalamus + internal capsule)
- ataxic hemiparesis (frontal lobe in white matter)
brainstem lesions
*clinical hallmark = CROSSED FINDINGS (one symptom on one side of the body and different signs on the other side)
blood supply of lateral midbrain
*PCA (and some SCA)
blood supply of medial midbrain
PCA / basilar
blood supply of lateral pons
AICA
blood supply of medial pons
basilar
blood supply of lateral medulla
PICA
blood supply of medial medulla
anterior spinal artery (ASA)
medial medullary syndrome
*anterior spinal artery stroke
*contralateral weakness
*contralateral loss of vibration and proprioception
*ipsilateral tongue deviation
*NO loss of pain/temp
lesion in frontal eye fields (FEF)
*ipsilateral gaze preference (eyes to side of lesion)
*cortical problem
lesion in paramedian pontine reticular formation (PPRF)
*brainstem gaze palsy (both eyes won’t move past midline at all TOWARDS the side of the lesion)
lesion in medial longitudinal fasciculus (MLF)
*internuclear ophthalmoplegia
(lesion in R MLF = right INO: right eye will not look medially when left eye is abducted, causing nystagmus in the left eye)
lesion in MLF + PPRF
*1 and 1/2 syndrome
(LEFT MLF and PPRF lesion:
-looking right: right eye will abduct to the R, left eye gets stuck at midline
-looking left: neither eye will move past midline)
lateral medullary syndrome
*PICA stroke
*contralateral sensory loss in the body
*ipsilateral sensory loss in the face
*hoarseness and dysphagia
*ipsilateral Horner’s
*ipsilateral ataxia
*NO motor weakness
*hiccups
medial pontine syndrome
*paramedian branches of the basilar stroke
*contralateral weakness
*contralateral vibration and proprioception loss
*weakness of ipsilateral eye abduction
lateral pontine syndrome
*AICA stroke
*ipsilateral facial weakness (upper and lower face b/c LMN lesion)
*ipsilateral gaze palsy
*ipsilateral deafness/hearing loss
*nausea/vertigo
*ipsilateral face numbness
*ipsilateral ataxia
*contralateral numbness of limbs
complete, bilateral pontine lesion
*locked-in syndrome
*comatose
*quadriparesis
*small, pinpoint pupils
*complete horizontal gaze palsy
dorsal midbrain syndrome (Parinaud)
*caused by pressure upon the superior colliculus and pre-tectal area
*paralysis of vertical gaze (inability to look up)
*light-near dissociation (loss of pupillary response to light, but retained pupil constriction with convergence)
*convergence-retraction nystagmus upon attempted up-gaze
Weber’s syndrome (ventro-medial midbrain)
*ipsilateral 3rd nerve palsy (eye down + out and dilated)
*contralateral hemiparesis (weakness - including face)
Benedickt syndrome (paramedian midbrain)
*ipsilateral 3rd nerve palsy
*contralateral ataxia
*contralateral loss of touch/vibration
localization for: pure motor hemiparesis lacunar stroke
*internal capsule (or ventral pons)
localization for: pure sensory lacunar stroke
*thalamus (if ALL sensory modalities)
localization for: clumsy-hand, dysarthria lacunar stroke
pons or internal capsule
localization for: sensorimotor lacunar stroke
thalamus + internal capsule
localization for: ataxic hemiparesis lacunar stroke
frontal lobe, in white matter
